The presently disclosed embodiment relates to an electromagnetic vibrating diaphragm pump to be used for aeration of a domestic septic tank, oxygen supply to a fish tank, air blow of a bubbling bath and other applied apparatuses.
An electromagnetic vibrating diaphragm pump undergoes suction and discharging of a fluid by driving diaphragms by carrying out reciprocating vibration of an oscillator having permanent magnets and connected to the diaphragms using a magnetic co-action with one electromagnet or with two electromagnets provided so as to locate the oscillator therebetween. The diaphragms are sandwiched between center plates comprising a pair of disc-like plates and are fixed to the oscillator via the center plates.
For fixing the diaphragm with the center plates, for example, there is a method of laying a disc-like diaphragm on the outer side of the disc-like center plate and subjecting a contact portion of the center plate and the diaphragm to welding with ultrasonic wave to fix them as disclosed in JP 2009-178981 A. Such a fixing method by ultrasonic welding is explained in detail by referring to FIG. 7. In addition, FIG. 8 shows a front view in the direction of M of FIG. 7, FIG. 9 shows a C-C cross-section of FIG. 8, and FIG. 10 shows a front view in the direction of N of FIG. 7.
FIG. 7 shows a disc-like diaphragm 104 and first and second plates 107a and 107b constituting the center plates for sandwiching the diaphragm 104. The first plate 107a is in the form of a disc having a through-hole H1 formed at its center, and has a receiving concave portion 133 for receiving a cylindrical portion 127 of the second plate 107b explained below as shown in FIGS. 11a and 11b. The second plate 107b is in the form of a disc having a through-hole H2 formed at its center, and comprises the cylindrical portion 127 formed at its center, a groove 128 formed along an outer periphery of the cylindrical portion 127, four holes 129 formed in the circumferential direction of the groove 128 at an interval of 90°, and a ring rib 132 formed at the external side in a radial direction of the holes 129 and pressing the surface of the diaphragm 104. Further, as shown in FIG. 10, at the second plate 107b side of the diaphragm 104, a raised ring portion 130 is provided at the external side in a radial direction of the through-hole 126 formed at the center of the diaphragm along the through-hole 126, and four protruded portions 131 extending from the outer periphery of the raised portion 130 at an interval of 90° in the circumferential direction of the raised portion 130 are provided.
When the diaphragm 104 and the first and second plates 107a and 107b constituting the center plates are in the shape shown in FIG. 7, the second plate 107b is assembled to the diaphragm 104 in such a manner that the cylindrical portion 127 of the second plate 107b is inserted through the through-hole 126 of the diaphragm 104, the raised portion 130 of the diaphragm 104 (see FIG. 10) is fitted into the groove 128 of the second plate 107b, and the protruded portions 131 of the diaphragm 104 (see FIG. 10) are fitted into the holes 129 of the second plate 107b. Further, the first plate 107a is assembled to the diaphragm 104 by ultrasonic welding of the first plate 107a and the cylindrical portion 127 of the second plate 107b protruded toward the first plate 107a side.
This ultrasonic welding is explained by means of FIGS. 11a and 11b. As shown in FIG. 11a, the bottom portion of the cylindrical portion 127 of the second plate 107b is tapered, and the corner of the receiving concave portion 133 of the first plate 107a is pressed onto this bottom portion and ultrasonic wave is applied to this pressed portion for welding (portions to be welded in the drawing). Thereby, as shown in FIG. 11b, a tapered meltable portion which is the bottom portion of the second plate 107b is melted (shown by a dotted pattern in the drawing), and is filled in a gap between the cylindrical portion 127 of the second plate 107b and the receiving concave portion 133. Thus, the first plate 107a can be assembled to the second plate 107b. 